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  • Author or Editor: Nicola J. Volstad x
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OBJECTIVE To determine variance effects influencing ground reaction forces (GRFs) in a heterogeneous population of lame dogs during trotting.

ANIMALS 30 client-owned dogs with thoracic limb lameness and 31 dogs with pelvic limb lameness.

PROCEDURES GRFs, velocity, height at the dorsal aspect of the scapulae (ie, withers), and shoulder height were obtained. Each dog was trotted across a force platform at its preferred velocity. Variance effects for 12 velocity and associated relative velocity (V*) ranges were examined.

RESULTS Individual dog, velocity, V*, and limb significantly influenced GRFs. Withers height V* ranges were associated with small variance in GRFs, but all absolute and V* ranges were associated with significant effects for all 4 limbs and both types of lameness. Significant changes in lame limb GRFs and velocity in ipsilateral trials in dogs with thoracic limb and pelvic limb lameness were evident with trial repetition. Withers height V* range of 0.55 to 0.93 captured a large proportion of trials (> 90%) in dogs with thoracic limb or pelvic limb lameness, with limited effects on peak vertical force and vertical impulse.

CONCLUSIONS AND CLINICAL RELEVANCE Trial repetition caused alterations to GRFs and subject velocity that may have confounded assessment of lameness, which supported the concept that a priori selection of a velocity or V* range for force platform gait analysis should use a range that captures valid trials efficiently while minimizing GRF variance. These ranges typically would span the preferred velocity of subject dogs, such as withers height V* of 0.55 to 0.93.

Full access
in American Journal of Veterinary Research


OBJECTIVE To develop contact time (ConT) and withers height-normalized relative ConT (ConT*) for force platform gait analysis of dogs.

ANIMALS 29 healthy client-owned dogs.

PROCEDURES Height at the most dorsal aspect of the shoulders (withers) was measured with a framing square. Dogs were trotted across a force platform at their preferred velocity with controlled acceleration (± 0.5 m/s2). Ranges of ConT and ConT* centered on the population mean ConT were created. Variance effects on ground reaction forces (GRFs) for 4 thoracic limb and 4 pelvic limb ConT and associated ConT* ranges were examined. Efficiency of trial capture and effects of velocity ranges on GRF variance were determined.

RESULTS Individual dogs had the greatest effect on GRF variance for thoracic and pelvic limbs. Narrow ConT and ConT* ranges had few significant effects on GRFs but were inefficient at capturing trials. The ConT ranges of 0.22 to 0.29 seconds and 0.19 to 0.25 seconds for thoracic and pelvic limbs, respectively, provided the most efficient rates of trial capture with the fewest significant effects on GRFs. Compared with ConT and ConT* ranges, relative velocity ranges had higher efficiency and smaller GRF variance effects.

CONCLUSIONS AND CLINICAL RELEVANCE Dogs of various morphologies have differing limb velocities. Use of ConT as a surrogate for limb velocity may improve GRF data quality. We identified ConT and ConT* ranges associated with low GRF variance. However, relative velocity ranges captured data more efficiently. Efficient capture of data may help avoid worsening of lameness during gait analysis of dogs.

Full access
in American Journal of Veterinary Research